Why are the materials of my objects not rendering?
You will laugh when you see how simple this is.

You have the material for your table leg set as the render layer material override. What that does is override all your materials with that one (and because only the books have a UV map you don't see that texture expect on the books.)

Simply clear the Material Override, switch back to cycles and it will render normally. (All your materials are for cycles, so none of them will work in the internal render.)



EDIT:

Newer versions of blender don't use layers, but "collections" so the override function is in the scene>View Layer section.



Additional info:

Where is the Layers panel in Blender 2.8?

2.8 - Is it possible to assign (override) a material to a whole collection?